An air-fuel ratio control device includes an air-fuel ratio sensor configured such that an output current value thereof varies linearly in accordance with an oxygen concentration, and air-fuel ratio feedback control means capable of executing air-fuel ratio feedback control for feedback-controlling a fuel injection amount on the basis of a detection value from the air-fuel ratio sensor so that exhaust gas of an internal combustion engine reaches a predetermined air-fuel ratio. The air-fuel ratio control device further includes prohibiting means for prohibiting the feedback control when the air-fuel ratio reaches or exceeds a predetermined rich air-fuel ratio. The air-fuel ratio control device permits the feedback control for a predetermined period after the air-fuel ratio reaches or exceeds the predetermined rich air-fuel ratio.